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146-610: The AJ-60A rocket motor was developed between 1999 and 2003 for use on the Atlas V. On January 19, 2006 the New Horizons spacecraft to Pluto was launched directly into a solar-escape trajectory at 16.26 kilometers per second (58,536 km/h; 36,373 mph) from Cape Canaveral using an Atlas V version with 5 of these SRBs and Star 48B third stage. New Horizons passed the Moon's orbit in just nine hours. In 2015, ULA announced that

292-423: A gravity assist that increased New Horizons ' speed; the flyby also enabled a general test of New Horizons ' scientific capabilities, returning data about the planet's atmosphere , moons , and magnetosphere . Most of the post-Jupiter voyage was spent in hibernation mode to preserve onboard systems, except for brief annual checkouts. On December 6, 2014, New Horizons was brought back online for

438-423: A latency of about 4.5 hours (one-way). The 70 m (230 ft) NASA Deep Space Network (DSN) dishes are used to relay commands once the spacecraft is beyond Jupiter. The spacecraft uses dual modular redundancy transmitters and receivers, and either right- or left-hand circular polarization . The downlink signal is amplified by dual redundant 12-watt traveling-wave tube amplifiers (TWTAs) mounted on

584-635: A stellar occultation , in which the object passes in front of a star from the vantage point of Earth. Since the occultation event is only visible from certain parts of the Earth, the New Horizons team combined data from Hubble and the European Space Agency 's Gaia space observatory to figure out exactly when and where on Earth's surface Arrokoth would cast a shadow. They determined that occultations would occur on 3 June, 10 July, and 17 July in 2017, and set off for places around

730-493: A change of plans such that the entire probe was rotated to make photos at Uranus and Neptune, similar to how New Horizons rotated. New Horizons carries seven instruments: three optical instruments, two plasma instruments, a dust sensor and a radio science receiver/radiometer. The instruments are to be used to investigate the global geology, surface composition, surface temperature, atmospheric pressure, atmospheric temperature and escape rate of Pluto and its moons. The rated power

876-532: A collection of images of New Horizons project personnel on another CD, a piece of Scaled Composites 's SpaceShipOne , a "Not Yet Explored" USPS stamp, and two copies of the Flag of the United States . About 30 grams (1 oz) of Clyde Tombaugh's ashes are aboard the spacecraft, to commemorate his discovery of Pluto in 1930. A Florida state quarter coin, whose design commemorates human exploration,

1022-456: A composite light shield and mount with titanium and fiberglass for thermal isolation. Overall mass is 8.6 kg (19 lb), with the optical tube assembly (OTA) weighing about 5.6 kg (12 lb), for one of the largest silicon-carbide telescopes flown at the time (now surpassed by Herschel ). For viewing on public web sites the 12-bit per pixel LORRI images are converted to 8-bit per pixel JPEG images. These public images do not contain

1168-750: A concept of what it might look like prior to spacecraft flyby. There were two potentially useful Arrokoth occultations predicted for 2018: one on 16 July and one on 4 August. Neither of these were as good as the three 2017 events. No attempts were made to observe the 16 July 2018 occultation, which took place over the South Atlantic and the Indian Ocean. For the 4 August 2018 event, two teams, consisting of about 50 researchers in total, went to locations in Senegal and Colombia. The event gathered media attention in Senegal, where it

1314-410: A connection with the spacecraft: the first letters of their names (N and H) are the initials of New Horizons . The moons' discoverers chose these names for this reason, plus Nix and Hydra's relationship to the mythological Pluto . In addition to the science equipment, there are nine cultural artifacts traveling with the spacecraft. These include a collection of 434,738 names stored on a compact disc,

1460-452: A dense, opaque region of the early Kuiper belt where the Sun appeared heavily obscured by dust. Icy particles within the early Kuiper belt experienced streaming instability , in which they slowed down due to drag against the surrounding gas and dust, and gravitationally coalesced into clumps of larger particles. Because there have been few to no disruptive impacts on Arrokoth since it formed,

1606-465: A distance of 3,538 km (2,198 mi), equivalent to a few minutes of travel at the craft's speed, and one third of the distance of the spacecraft's closest encounter with Pluto. Closest approach occurred on 1 January 2019, at 05:33 UTC ( Spacecraft Event Time – SCET) at which point it was 43.4  AU from the Sun in the direction of the constellation Sagittarius . At this distance,

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1752-455: A flyby on 1 January 2019. Arrokoth is a contact binary 36 km (22 mi) long, composed of two planetesimals 21 and 15 km (13 and 9 mi) across, that are joined along their major axes. With an orbital period of about 298 years and a low orbital inclination and eccentricity , Arrokoth is classified as a cold classical Kuiper belt object . Arrokoth was discovered on 26 June 2014 by astronomer Marc Buie and

1898-430: A full orbit around the Sun. Having a low orbital eccentricity of 0.042, Arrokoth follows a nearly circular orbit around the Sun, only slightly varying in distance from 42.7 AU at perihelion to 46.4 AU at aphelion . Because Arrokoth has a low orbital eccentricity, it does not approach close enough to Neptune for its orbit to become perturbed . (Arrokoth's minimum orbital intersection distance from Neptune

2044-411: A higher elevation and tilt than the others. Akasa Linea, the neck region connecting the two lobi, has a brighter and less red appearance than the surfaces of either lobus. The brightness of Akasa Linea is likely due to a composition of a more reflective material than the surfaces of the lobi. One hypothesis suggests the bright material originated in the deposition of small particles that had fallen from

2190-447: A longer period of time, and may likely account for the reddening and production of tholins on Arrokoth. The photoionization of organic compounds and volatiles on Arrokoth was also thought to produce hydrogen gas that would interact with the solar wind , though New Horizons 's SWAP and PEPSSI instruments did not detect any signature of solar wind interaction around Arrokoth. From color and spectral measurements of Arrokoth,

2336-498: A low frequency of impact events along with the slow speeds of impacts, Arrokoth's surface would remain preserved since its formation. The preserved surface of Arrokoth could possibly give hints to its formation process, as well as signs of accreted material. Numerous small pits on Arrokoth's surface were identified in high resolution images from the New Horizons spacecraft. The size of these pits are measured at about 700 m (2,300 ft) across. The exact cause of these pits

2482-562: A naming theme for all features of Arrokoth, which are to be named after words for "sky" in the languages of the world, past and present. In 2021, the first few names were approved, including Sky Crater on the small lobe, later named Weeyo Lobus. In 2022, Kaʼan Arcus was approved for the circular arc on Wenu Lobus. Topography variations at the limb of Arrokoth suggest that its interior is likely composed of mechanically strong material consisting of mostly amorphous water ice and rocky material. Trace amounts of methane and other volatile gases in

2628-692: A series of proposed Pluto missions leading up to New Horizons . Stamatios "Tom" Krimigis , head of the Applied Physics Laboratory 's space division, one of many entrants in the New Frontiers Program competition, formed the New Horizons team with Alan Stern in December 2000. Appointed as the project's principal investigator , Stern was described by Krimigis as "the personification of the Pluto mission". New Horizons

2774-598: A slower trajectory directly to Pluto, delaying its encounter by five to six years. 486958 Arrokoth 486958 Arrokoth ( provisional designation 2014 MU 69 ; formerly nicknamed Ultima Thule ) is a trans-Neptunian object located in the Kuiper belt . Arrokoth became the farthest and most primitive object in the Solar System visited by a spacecraft when the NASA space probe New Horizons conducted

2920-482: A triangle, almost 0.76 m (2.5 ft) thick. (The Pioneers have hexagonal bodies, whereas the Voyagers , Galileo , and Cassini–Huygens have decagonal , hollow bodies.) A 7075 aluminium alloy tube forms the main structural column, between the launch vehicle adapter ring at the "rear", and the 2.1 m (6 ft 11 in) radio dish antenna affixed to the "front" flat side. The titanium fuel tank

3066-455: A very low mechanical strength in order to merge and form compact bodies at these speeds. The central unit ('mh') is encircled by a bright annular feature, Kaʼan Arcus (initially dubbed "The Road to Nowhere"). From stereographic analysis, the central unit appears to be relatively flat compared to the surrounding units. Stereographic analysis of Arrokoth has also shown that one particular unit located at Wenu's limb ('md') appears to have

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3212-527: A visible-light CCD imager with broadband and color channels; and LEISA (Linear Etalon Imaging Spectral Array), a near- infrared imaging spectrometer. LEISA is derived from a similar instrument on the Earth Observing-1 spacecraft. Ralph was named after Alice's husband on The Honeymooners , and was designed after Alice. On June 23, 2017, NASA announced that it has renamed the LEISA instrument to

3358-457: Is 21 watts , though not all instruments operate simultaneously. In addition, New Horizons has an Ultrastable Oscillator subsystem, which may be used to study and test the Pioneer anomaly towards the end of the spacecraft's life. The Long-Range Reconnaissance Imager (LORRI) is a long-focal-length imager designed for high resolution and responsivity at visible wavelengths. The instrument

3504-535: Is 12.75 AU.) Arrokoth's orbit appears to be stable over the long term; simulations by the Deep Ecliptic Survey show that its orbit will not significantly change over the next 10 million years. At the time of the New Horizons flyby in January ;2019, Arrokoth's distance from the Sun was 43.28 AU (6.47 × 10 ^  km; 4.02 × 10 ^  mi). At this distance, light from

3650-456: Is also enclosed in blankets that extend to the body. The heat from the RTG adds warmth to the spacecraft while it is in the outer Solar System. While in the inner Solar System, the spacecraft must prevent overheating, hence electronic activity is limited, power is diverted to shunts with attached radiators, and louvers are opened to radiate excess heat. While the spacecraft is cruising inactively in

3796-709: Is an interplanetary space probe launched as a part of NASA 's New Frontiers program . Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institute (SwRI), with a team led by Alan Stern , the spacecraft was launched in 2006 with the primary mission to perform a flyby study of the Pluto system in 2015, and a secondary mission to fly by and study one or more other Kuiper belt objects (KBOs) in

3942-609: Is approximately $ 700 million over 15 years (2001–2016). The spacecraft was built primarily by Southwest Research Institute (SwRI) and the Johns Hopkins Applied Physics Laboratory. The mission's principal investigator is Alan Stern of the Southwest Research Institute (formerly NASA Associate Administrator). After separation from the launch vehicle, overall control was taken by Mission Operations Center (MOC) at

4088-742: Is clad in iridium , then encased in a graphite shell. It was developed by the U.S. Department of Energy at the Materials and Fuels Complex, a part of the Idaho National Laboratory . The original RTG design called for 10.9 kg (24 lb) of plutonium, but a unit less powerful than the original design goal was produced because of delays at the United States Department of Energy, including security activities, that delayed plutonium production. The mission parameters and observation sequence had to be modified for

4234-455: Is designed to act as shielding , reducing electronics errors caused by radiation from the RTG. Also, the mass distribution required for a spinning spacecraft demands a wider triangle. The interior structure is painted black to equalize temperature by radiative heat transfer. Overall, the spacecraft is thoroughly blanketed to retain heat. Unlike the Pioneers and Voyagers , the radio dish

4380-468: Is determined to be 15.938 hours. Due to the high axial tilt of its rotation, the solar irradiance of the northern and southern hemispheres of Arrokoth varies greatly over the course of its orbit around the Sun. As it orbits around the Sun, one polar region of Arrokoth faces the Sun continuously while the other faces away. The solar irradiance of Arrokoth varies by 17 percent due to the low eccentricity of its orbit. The average temperature of Arrokoth

4526-435: Is either pointed toward the Earth or is being viewed at an equator-on configuration with a nearly spherical shape, with a constrained a / b best-fit aspect ratio around 1.0–1.15. Upon the New Horizons spacecraft's approach to Arrokoth, no rotational light curve amplitude was detected by the spacecraft despite Arrokoth's irregular shape. To explain the lack of its rotational light curve, scientists surmised that Arrokoth

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4672-405: Is emitted from Arrokoth's subsurface, which was predicted to be intrinsically warmer than the exterior surface. The mass and density of Arrokoth are unknown. A definitive mass and density estimate cannot be given as the lobi are in contact rather than orbiting each other. Although a possible natural satellite orbiting Arrokoth could help determine its mass, no such satellites were found. Under

4818-562: Is equipped with a 1024×1024 pixel by 12-bits-per-pixel monochromatic CCD imager giving a resolution of 5  μrad (~1  arcsec ). The CCD is chilled far below freezing by a passive radiator on the antisolar face of the spacecraft. This temperature differential requires insulation and isolation from the rest of the structure. The 208.3 mm (8.20 in) aperture Ritchey–Chretien mirrors and metering structure are made of silicon carbide to boost stiffness, reduce weight and prevent warping at low temperatures. The optical elements sit in

4964-549: Is estimated to be around 42 K (−231.2 °C; −384.1 °F), with a maximum of around 60 K on the illuminated subsolar point of Arrokoth. Radiometric measurements from the New Horizons REX instrument indicate that the mean surface temperature of Arrokoth's unilluminated face is about 29 ± 5 K , higher than the modeled range of 12–14 K . The higher temperature of Arrokoth's unilluminated face as measured by REX implies that thermal radiation

5110-530: Is glossed as 'sky', and this was the meaning intended by the New Horizons team, but it would seem that it actually meant 'cloud'. Arrokoth is a contact binary consisting of two lobes (lobi) attached by a narrow neck or waist, which is encircled by a bright band named Akasa Linea . The lobi were likely once two objects that later merged in a slow collision. The larger lobus, Wenu, is measured at about 21.6 km (13.4 mi) across its longest axis while

5256-413: Is in this tube. The RTG attaches with a 4-sided titanium mount resembling a gray pyramid or stepstool. Titanium provides strength and thermal isolation. The rest of the triangle is primarily sandwich panels of thin aluminum face sheet (less than 1 ⁄ 64  in or 0.40 mm) bonded to aluminum honeycomb core. The structure is larger than strictly necessary, with empty space inside. The structure

5402-510: Is inclined to the ecliptic plane by 2.45 degrees, relatively low compared to other classical Kuiper belt objects such as Makemake . Since Arrokoth has a low orbital inclination and eccentricity, it is part of the dynamically cold population of classical Kuiper belt objects, which are unlikely to have undergone significant perturbations by Neptune during its outward migration in the past. The cold classical population of Kuiper belt objects are thought to be remnant planetesimals left over from

5548-541: Is included, officially as a trim weight, as is a Maryland state quarter to honor the probe's builders. One of the science packages (a dust counter) is named after Venetia Burney , who, as a child, suggested the name "Pluto" after its discovery. The goal of the mission is to understand the formation of the Plutonian system, the Kuiper belt, and the transformation of the early Solar System. The spacecraft collected data on

5694-451: Is less flattened, with dimensions of 15 km × 14 km × 10 km (9.3 mi × 8.7 mi × 6.2 mi). As a whole, Arrokoth is 36 km (22 mi) across its longest axis and is about 10 km (6.2 mi) thick, with the centers of the lobi separated from each other by 17.2 km (10.7 mi). Given the volume equivalent lobus diameters of 15.9 km (9.9 mi) and 12.9 km (8.0 mi),

5840-712: Is redder than that of Pluto , thus it belongs to the "ultra red" population of cold classical Kuiper belt objects. The red coloration of Arrokoth is caused by the presence of a mix of complex organic compounds called tholins , which are produced from the photolysis of various simple organic and volatile compounds by cosmic rays and ultraviolet solar radiation. The presence of sulfur-rich tholins on Arrokoth's surface implies that volatiles such as methane, ammonia , and hydrogen sulfide were once present on Arrokoth, but were quickly lost due to Arrokoth's small mass. However, less volatile materials such as methanol, acetylene , ethane , and hydrogen cyanide could be retained over

5986-428: Is rotating on its side, with its rotational axis pointing nearly directly at the approaching New Horizons spacecraft. Subsequent images of Arrokoth from New Horizons upon approach confirmed that its rotation is tilted, with its south pole facing towards the Sun. The rotational axis of Arrokoth is tilted 99  degrees to its orbit. Based on occultation and New Horizons imaging data, Arrokoth's rotation period

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6132-656: Is the Mongoose-V , a 12 MHz radiation-hardened version of the MIPS R3000 CPU . Multiple redundant clocks and timing routines are implemented in hardware and software to help prevent faults and downtime. To conserve heat and mass, spacecraft and instrument electronics are housed together in IEMs (integrated electronics modules). There are two redundant IEMs. Including other functions such as instrument and radio electronics, each IEM contains 9 boards. The software of

6278-580: Is the lead on the New Horizons navigation team and is responsible for planning trajectory adjustments as the spacecraft speeds toward the outer Solar System . Coincidentally the Naval Observatory Flagstaff Station was where the photographic plates were taken for the discovery of Pluto's moon Charon . The Naval Observatory itself is not far from the Lowell Observatory where Pluto was discovered. New Horizons

6424-430: Is the northernmost location mentioned in ancient Greek and Roman literature and cartography , while in classical and medieval literature ultima Thule (Latin for 'farthermost Thule') acquired a metaphorical meaning of any distant place located beyond the "borders of the known world". Once it was determined that the body was a bilobate contact binary, the New Horizons team nicknamed the larger lobus "Ultima" and

6570-407: Is to extend operations for New Horizons until the spacecraft exits the Kuiper belt, which is expected to occur between 2028 and 2029. In August 1992, JPL scientist Robert Staehle called Pluto discoverer Clyde Tombaugh , requesting permission to visit his planet. "I told him he was welcome to it," Tombaugh later remembered, "though he's got to go one long, cold trip." The call eventually led to

6716-429: Is unknown; several explanations for these pits include impact events, the collapse of material, the sublimation of volatile materials, or the venting and escape of volatile gases from the interior of Arrokoth. The surfaces of each lobus of Arrokoth display regions of varying brightness along with various geological features such as troughs and hills . These geological features are thought to have originated from

6862-682: Is used as a pressurant, with an elastomeric diaphragm assisting expulsion. The spacecraft's on-orbit mass including fuel is over 470 kg (1,040 lb) on the Jupiter flyby trajectory, but would have been only 445 kg (981 lb) for the backup direct flight option to Pluto. Significantly, had the backup option been taken, this would have meant less fuel for later Kuiper belt operations. There are 16 thrusters on New Horizons : four 4.4  N (1.0  lbf ) and twelve 0.9 N (0.2 lbf) plumbed into redundant branches. The larger thrusters are used primarily for trajectory corrections, and

7008-556: The New Horizons Search Team using the Hubble Space Telescope as part of a search for a Kuiper-belt object for New Horizons to target in its first extended mission; it was chosen over two other candidates, 2014 OS 393 and 2014 PN 70 , to become the primary target of the mission. When Arrokoth was first observed by the Hubble Space Telescope in 2014, it was designated 1110113Y in

7154-758: The Atlas V 's kerosene tank. Further delays related to low cloud ceiling conditions downrange , and high winds and technical difficulties—unrelated to the rocket itself—prevented launch for a further two days. The probe finally lifted off from Pad 41 at Cape Canaveral Air Force Station , Florida , directly south of Space Shuttle Launch Complex 39 , at 19:00 UTC on January 19, 2006. The Centaur second stage ignited at 19:04:43 UTC and burned for 5 minutes 25 seconds. It reignited at 19:32 UTC and burned for 9 minutes 47 seconds. The ATK Star 48 B third stage ignited at 19:42:37 UTC and burned for 1 minute 28 seconds. Combined, these burns successfully sent

7300-879: The Johns Hopkins University Applied Physics Laboratory , which were prominently involved in Arrokoth's discovery, were both operated from the Tidewater region of Maryland. With the permission of the elders of the Pamunkey Indian Tribe of the Powhatan nation, the name Arrokoth was proposed to the IAU and formally announced by the New Horizons team in a ceremony held at the NASA Headquarters in

7446-520: The New Horizons spacecraft made four course changes in October and November 2015 to place itself on a trajectory towards Arrokoth. It is the first object to be targeted for a flyby that was discovered after the visiting spacecraft was launched, and is the farthest object in the Solar System ever to be visited by a spacecraft. Moving at a speed of 51,500 km/h (858 km/min; 14.3 km/s; 32,000 mph) New Horizons passed by Arrokoth at

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7592-570: The New Horizons spacecraft, a " hydrogen wall " at the outer edges of the Solar System that was first detected in 1992 by the two Voyager spacecraft . The Ralph telescope, 75 mm in aperture, is one of two photographic instruments that make up New Horizons ' Pluto Exploration Remote Sensing Investigation (PERSI), with the other being the Alice instrument. Ralph has two separate channels: MVIC (Multispectral Visible Imaging Camera),

7738-512: The New Horizons team began their search for potential targets. While digitally processing images from Hubble, Arrokoth was identified by astronomer Marc Buie , member of the New Horizons team. Buie reported his finding to the search team for subsequent analysis and confirmation. Arrokoth was the second object found during the search, after 2014 MT 69 . Three more candidate targets were later discovered with Hubble, though follow-up astrometric observations eventually ruled them out. Of

7884-733: The University of Colorado Boulder , led by principal investigator Larry W. Esposito , and supported by the JPL, Lockheed Martin and the University of California . However, the APL, in addition to being supported by Pluto Kuiper Express developers at the Goddard Space Flight Center and Stanford University were at an advantage; they had recently developed NEAR Shoemaker for NASA, which had successfully entered orbit around 433 Eros earlier that year, and would later land on

8030-498: The Voyager program probes, had a rotatable instrumentation platform (a "scan platform") that could take measurements from virtually any angle without losing radio contact with Earth. New Horizons was mechanically simplified to save weight, shorten the schedule, and improve reliability during its 15-year designed lifetime. The Voyager 2 scan platform jammed at Saturn, and the demands of long time exposures at outer planets led to

8176-407: The high-gain antenna , there are two backup low-gain antennas and a medium-gain dish. The high-gain dish has a Cassegrain reflector layout, composite construction, of 2.1-meter (7 ft) diameter providing over 42  dBi of gain and a half-power beam width of about a degree. The prime-focus medium-gain antenna, with a 0.3-meter (1 ft) aperture and 10° half-power beam width, is mounted to

8322-522: The radioactive decay of radionuclides , the trapped volatile gases inside Arrokoth would migrate outward and escape from the surface, similarly to the scenario of outgassing of comets . The escaped gases may subsequently freeze and deposit on Arrokoth's surface, and could possibly account for the presence of ices and tholins on its surface. Arrokoth orbits the Sun at an average distance of 44.6 astronomical units (6.67 × 10 ^  km; 4.15 × 10 ^  mi), taking 297.7 years to complete

8468-608: The "Lisa Hardaway Infrared Mapping Spectrometer" in honor of Lisa Hardaway , the Ralph program manager at Ball Aerospace , who died in January 2017 at age 50. The Venetia Burney Student Dust Counter (VBSDC), built by students at the University of Colorado Boulder, is operating periodically to make dust measurements. It consists of a detector panel, about 460 mm × 300 mm (18 in × 12 in), mounted on

8614-596: The 17 July 2017 occultation. No brightness changes of the target star have been seen by Hubble, ruling out any optically thick rings or debris down to 1,600 km (990 mi) from Arrokoth. Results of the 2017 and 2018 occultation campaigns were presented at the 50th meeting of the American Astronomical Society Division for Planetary Sciences on 26 October 2018. Having completed its flyby of Pluto in July ;2015,

8760-704: The Applied Physics Laboratory in Howard County, Maryland . The science instruments are operated at Clyde Tombaugh Science Operations Center (T-SOC) in Boulder, Colorado . Navigation is performed at various contractor facilities, whereas the navigational positional data and related celestial reference frames are provided by the Naval Observatory Flagstaff Station through Headquarters NASA and JPL . KinetX

8906-467: The Atlas V will switch to new GEM 63 boosters produced by Northrop Grumman Innovation Systems . (GEM 63XL, a stretched version of the GEM 63 booster will be used on the upcoming Vulcan rocket.) The first Atlas V launched with GEM 63 boosters on November 13, 2020. AJ-60A is a solid fueled rocket burning HTPB -based composite solid propellant . The casing is composed of a graphite - epoxy composite, and

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9052-453: The District of Columbia on 12 November 2019. Prior to the ceremony, the name was accepted by the IAU's Minor Planet Center on 8 November, and the New Horizons team's naming citation was published in a Minor Planet Circular on 12 November. The Powhatan language became extinct in the late 18th century and little was recorded of it. In an old word list, arrokoth

9198-598: The Hubble Space Telescope in June and July 2017 revealed that the telescopes had been placed in the wrong location, and that these estimations were incorrect. On 10 July 2017, the airborne telescope SOFIA was successfully placed close to the predicted centerline for the second occultation while flying over the Pacific Ocean from Christchurch , New Zealand. The main purpose of those observations

9344-567: The Kuiper belt, are speculative. The VBSDC is always turned on measuring the masses of the interplanetary and interstellar dust particles (in the range of nano- and picograms) as they collide with the PVDF panels mounted on the New Horizons spacecraft. The measured data is expected to greatly contribute to the understanding of the dust spectra of the Solar System. The dust spectra can then be compared with those from observations of other stars, giving new clues as to where Earth-like planets can be found in

9490-704: The Minor Planet Center. Hubble Space Telescope observations in May and July 2015 as well as in July and October 2016 have greatly reduced the uncertainties in Arrokoth's orbit, which prompted the Minor Planet Center to assign its permanent minor planet number. In contrast to the orbit calculated by the Minor Planet Center, Arrokoth's observation arc in the JPL Small-Body Database does not include these additional observations and purports

9636-413: The Pacific Ocean. On 3 June 2017, two teams of NASA scientists tried to detect the shadow of Arrokoth from Argentina and South Africa. When they found that none of their telescopes had observed the object's shadow, it was initially speculated that Arrokoth might be neither as large nor as dark as previously expected, and that it might be highly reflective or even a swarm. Additional data taken with

9782-499: The Pluto encounter, and instrument check-out began. On January 15, 2015, the spacecraft began its approach phase to Pluto. On July 14, 2015, at 11:49  UTC , it flew 12,500 km (7,800 mi) above the surface of Pluto, which at the time was 34 AU from the Sun, making it the first spacecraft to explore the dwarf planet. In August 2016, New Horizons was reported to have traveled at speeds of more than 84,000 km/h (52,000 mph). On October 25, 2016, at 21:48 UTC,

9928-789: The Science Mission Directorate, Ed Weiler , prompted Stern to lobby for the funding of New Horizons in hopes of the mission appearing in the Planetary Science Decadal Survey , a prioritized "wish list," compiled by the United States National Research Council , that reflects the opinions of the scientific community. After an intense campaign to gain support for New Horizons , the Planetary Science Decadal Survey of 2003–2013

10074-441: The Sun continuously for half of its orbital period, resulting in extensive heating and consequent sublimation and loss of frozen volatiles at Arrokoth's poles. Regardless of the uncertainty surrounding the mechanisms for the flattening of Arrokoth, the subsequent merging of the bodies ancestral to the lobi appeared to be gentle. The present appearance of Arrokoth does not indicate deformation or compression fractures, suggesting that

10220-422: The Sun takes over six hours to reach Arrokoth. Arrokoth has last passed aphelion around 1906 and is currently approaching the Sun at a rate of approximately 0.13 AU per year, or about 0.6 kilometers per second (1,300 mph). Arrokoth will approach perihelion by 2055. Having an observation arc of 851 days, Arrokoth's orbit is fairly well-determined, with an uncertainty parameter of 2 according to

10366-421: The accretion of material during the formation of the Solar System . Results from photometric Hubble Space Telescope observations show that the brightness of Arrokoth varies by around 0.3  magnitudes as it rotates. Though the rotation period and light curve amplitude of Arrokoth could not be determined from Hubble observations, the subtle brightness variations suggested that Arrokoth's rotational axis

10512-505: The angle to the Sun, whereas the other measures spin rate and clocking. A cylindrical radioisotope thermoelectric generator (RTG) protrudes in the plane of the triangle from one vertex of the triangle. The RTG provided 245.7  W of power at launch, and was predicted to drop approximately 3.5  W every year, decaying to 202 W by the time of its encounter with the Plutonian system in 2015 and will decay too far to power

10658-427: The anti-solar face of the spacecraft (the ram direction), and an electronics box within the spacecraft. The detector contains fourteen polyvinylidene difluoride (PVDF) panels, twelve science and two reference, which generate voltage when impacted. Effective collecting area is 0.125 m (1.35 sq ft). No dust counter has operated past the orbit of Uranus ; models of dust in the outer Solar System, especially

10804-433: The assumption that both lobi are bound by self-gravity, with the mutual gravity of the two overcoming centrifugal forces that would otherwise separate them, Arrokoth is estimated to have a very low density similar to that of comets, with an estimated minimum density of 0.29 g/cm . In order to maintain the shape of the neck, the density of Arrokoth must be less than the maximum possible density of 1 g/cm , otherwise

10950-565: The asteroid to scientific and engineering fanfare. In November 2001, New Horizons was officially selected for funding as part of the New Frontiers program. However, the new NASA Administrator appointed by the Bush administration , Sean O'Keefe , was not supportive of New Horizons and effectively canceled it by not including it in NASA's budget for 2003. NASA's Associate Administrator for

11096-583: The atmospheres, surfaces, interiors, and environments of Pluto and its moons. It will also study other objects in the Kuiper belt. "By way of comparison, New Horizons gathered 5,000 times as much data at Pluto as Mariner did at the Red Planet ." Some of the questions the mission attempts to answer are: What is Pluto's atmosphere made of and how does it behave? What does its surface look like? Are there large geological structures? How do solar wind particles interact with Pluto's atmosphere? Specifically,

11242-505: The body under the dish. The receivers are low-power designs. The system can be controlled to power both TWTAs at the same time, and transmit a dual-polarized downlink signal to the DSN that nearly doubles the downlink rate. DSN tests early in the mission with this dual polarization combining technique were successful, and the capability was declared to be operational (when the spacecraft power budget permits both TWTAs to be powered). In addition to

11388-561: The cloud, caused the pair to slowly spiral closer until they touched—where over time the joints fused together, forming its present bilobate shape. In an alternative hypothesis formulated by researchers of the Chinese Academy of Sciences and the Max Planck Institute in 2020, the flattening of Arrokoth may have resulted from the process of sublimation-driven mass loss over a timescale of several million years after

11534-450: The clumping of smaller planetesimals that come to form the lobi of Arrokoth. The brighter regions of Arrokoth's surface, especially its bright lineation features, are thought to have resulted from the deposition of material that have rolled down from hills on Arrokoth, as surface gravity on Arrokoth is sufficient for this to occur. The smaller lobus, Weeyo, bears a large depression feature named 'Sky' (previously dubbed 'Maryland' after

11680-404: The coalescence of smaller planetesimal units prior to merging with the smaller object. The larger lobus Wenu appears to be an aggregate of 8 or so smaller components, each approximately 5 km (3 mi) across. It is unclear how Arrokoth has attained its present flattened shape, though two leading hypotheses have been postulated to explain the mechanisms leading to its flattened shape during

11826-414: The cold outer Solar System, the louvers are closed, and the shunt regulator reroutes power to electric heaters . New Horizons has both spin-stabilized (cruise) and three-axis stabilized (science) modes controlled entirely with hydrazine monopropellant . Additional post launch delta- v of over 290 m/s (1,000 km/h; 650 mph) is provided by a 77 kg (170 lb) internal tank. Helium

11972-554: The communications channels. These are small enough to fit on a single card. Because there are two redundant communications subsystems, there are two, identical REX circuit boards. On September 24, 2005, the spacecraft arrived at the Kennedy Space Center on board a C-17 Globemaster III for launch preparations. The launch of New Horizons was originally scheduled for January 11, 2006, but was initially delayed until January 17, 2006, to allow for borescope inspections of

12118-638: The context of the telescope's search for Kuiper belt objects, and was nicknamed "11" for short. Its existence as a potential target of the New Horizons probe was announced by NASA in October 2014 and it was unofficially designated as "Potential Target 1", or PT1 . Its official provisional designation , 2014 MU 69 , was assigned by the Minor Planet Center in March ;2015, after sufficient orbital information had been gathered. The provisional designation indicates that Arrokoth

12264-455: The data to Earth. Data storage is done on two low-power solid-state recorders (one primary, one backup) holding up to 8  gigabyte s each. Because of the extreme distance from Pluto and the Kuiper belt, only one buffer load at those encounters can be saved. This is because New Horizons would require approximately 16 months after leaving the vicinity of Pluto to transmit the buffer load back to Earth. At Pluto's distance, radio signals from

12410-429: The decade to follow, which became a mission to 486958 Arrokoth . It is the fifth space probe to achieve the escape velocity needed to leave the Solar System . On January 19, 2006, New Horizons was launched from Cape Canaveral Air Force Station by an Atlas V rocket directly into an Earth-and-solar escape trajectory with a speed of about 16.26 km/s (10.10 mi/s; 58,500 km/h; 36,400 mph). It

12556-474: The depression. Four subparallel troughs are present near the terminator of Weeyo, along with two possible kilometer-sized impact craters on the rim of Sky. The surface of Weeyo exhibits bright mottled regions separated by broad, dark regions ( dm ) which may have undergone scarp retreat , in which they were eroded due to the sublimation of volatiles, exposing lag deposits of darker material irradiated by sunlight. Another bright region ( rm ), located at

12702-440: The details of its formation have been preserved. From the differing present appearances of the lobi, each is thought to have accreted separately while in orbit around each other. Both progenitor objects are believed to have formed from a single source of material as they appear to be homogeneous in albedo, color, and composition. The presence of rolling topography units on the larger object indicates that it had likely formed from

12848-495: The engine throat and nozzle are made of carbon - phenolic composite. As configured for use on Atlas V, the nozzle is fixed at a 3 degree cant away from the attachment point, but Aerojet offers a variant with thrust vectoring capability. The Atlas V configuration also features an inward slanting nosecone , but it is available with a conventional nosecone or none at all for use on other rockets. The stages are designed to be transported by truck. New Horizons New Horizons

12994-399: The equatorial end of Weeyo, exhibits rough terrain along with several topographic features that have been identified as possible pits, craters, or mounds. Weeyo does not display distinct units of rolling topography near Sky, likely as a result of resurfacing caused by the impact event that created the crater. As on Weeyo, troughs and pit crater chains are also present along the terminator of

13140-588: The equivalent radiation of 80% the average annual dosage in North America from background radiation over an area with a radius of 105 km (65 mi). The spacecraft carries two computer systems: the Command and Data Handling system and the Guidance and Control processor. Each of the two systems is duplicated for redundancy , for a total of four computers. The processor used for its flight computers

13286-438: The existence of a " hydrogen wall " at the outer edges of the Solar System . This "wall" was first detected in 1992 by the two Voyager spacecraft . New Horizons is traveling through the Kuiper belt; it is 60.99  AU (9.12  billion   km ; 5.67 billion  mi ) from Earth and 60.37  AU (9.03  billion   km ; 5.61 billion  mi ) from the Sun as of November 2024. NASA has announced it

13432-492: The far and extreme ultraviolet (from 50– 180  nm ), over 32 view fields. Its goal is to determine the composition of Pluto's atmosphere. This Alice instrument is derived from another Alice aboard ESA 's Rosetta spacecraft. The instrument has a mass of 4.4 kg and draws 4.4 watts of power. Its primary role is to determine the relative concentrations of various elements and isotopes in Pluto's atmosphere. In August 2018, NASA confirmed, based on results by Alice on

13578-546: The five potential targets found with Hubble, Arrokoth was deemed to be the most feasible target for the spacecraft as the flyby trajectory required the least amount of fuel compared to that for 2014 PN 70 , the second most feasible target for New Horizons . On 28 August 2015, Arrokoth was officially selected by NASA as a flyby target for the New Horizons spacecraft. Arrokoth is too small and distant for its shape to be observed directly from Earth, but scientists were able to take advantage of an astronomical event called

13724-443: The form of complex macromolecules . Arrokoth's spectrum shares similarities with that of 2002 VE 95 and the centaur 5145 Pholus , which also display strong red spectral slopes along with signs of methanol present on their surfaces. Preliminary observations by the Hubble Space Telescope in 2016 revealed that Arrokoth has a red coloration, similar to other Kuiper belt objects and centaurs like Pholus . Arrokoth's color

13870-401: The form of vapors may also be present in Arrokoth's interior, trapped in water ice. Under the assumption that Arrokoth has a low comet-like density of around 0.5 g/cm , its internal structure is expected to be porous , as volatile gases trapped in Arrokoth's interior are thought to escape from the interior to the surface. Assuming that Arrokoth may have an internal heat source caused by

14016-523: The formation of the Solar System. The New Horizons team hypothesizes that the two progenitor objects formed with initially rapid rotations, causing their shapes to become flattened due to centrifugal forces. Over time, the rotation rates of the progenitor objects gradually slowed down as they experienced impacts by small objects and transferred their angular momentum to other orbiting debris left over from their formation. Eventually, loss of momentum, caused by impacts and momentum shifting to other bodies in

14162-515: The forward-facing side of the high-gain antenna's secondary reflector. The forward low-gain antenna is stacked atop the feed of the medium-gain antenna. The aft low-gain antenna is mounted within the launch adapter at the rear of the spacecraft. This antenna was used only for early mission phases near Earth, just after launch and for emergencies if the spacecraft had lost attitude control. New Horizons recorded scientific instrument data to its solid-state memory buffer at each encounter, then transmitted

14308-426: The full dynamic range of brightness information available from the raw LORRI images files. Solar Wind Around Pluto (SWAP) is a toroidal electrostatic analyzer and retarding potential analyzer (RPA), that makes up one of the two instruments comprising New Horizons ' Plasma and high-energy particle spectrometer suite (PAM), the other being PEPSSI. SWAP measures particles of up to 6.5 keV and, because of

14454-451: The home state of the New Horizons team). Assuming Sky has a circular shape, its diameter is 6.7 km (4.2 mi), with a depth of 0.51 km (0.32 mi). Sky is likely an impact crater that was formed by an object 700 m (2,000 ft) across. Two notably bright streaks of similar size are present within Sky, and may be remnants of avalanches where bright material rolled into

14600-482: The larger lobus Wenu. Wenu consists of eight distinctive units or blocks of rolling topography, each similarly sized at around 5 km (3.1 mi). The units are separated by relatively bright boundary regions. The similar sizes of the units suggests that each was once a small planetesimal, and that they coalesced to form Wenu. The planetesimals are expected to have accreted slowly by astronomical standards (at speeds of several meters per second), though they must have

14746-455: The last recorded data from the Pluto flyby was received from New Horizons . Having completed its flyby of Pluto, New Horizons then maneuvered for a flyby of Kuiper belt object 486958 Arrokoth (then nicknamed Ultima Thule ), which occurred on January 1, 2019, when it was 43.4  AU (6.49  billion   km ; 4.03 billion  mi ) from the Sun . In August 2018, NASA cited results by Alice on New Horizons to confirm

14892-512: The limits of photographic resolution), implying a paucity of impacts throughout its history. The occurrence of impact events in the Kuiper belt is thought to be uncommon, with a very low impact rate over the course of one billion years. Due to the slower orbital speeds of Kuiper belt objects, the speed of objects impacting Arrokoth is expected to be low, with typical impact speeds around 300 m/s (980 ft/s). At such slow impact speeds, large craters on Arrokoth are expected to be rare. With

15038-409: The lobi over time. Since Arrokoth's center of gravity lies between the lobi, small particles are likely to roll down the steep slopes toward the center between each lobus. Another proposal suggests the bright material is produced by the deposition of ammonia ice. Ammonia vapor present on the surface of Arrokoth would solidify around Akasa Linea, where gases cannot escape due to the concave shape of

15184-525: The lobi suggests that they were mutually locked to each other, likely due to tidal forces , before merging. The alignment of the lobi supports the idea that the two had individually formed from the coalescence of a cloud of icy particles. Measurements of Arrokoth's absorption spectrum by New Horizons 's LEISA spectrometer show that Arrokoth's spectrum exhibits a strong red spectral slope extending from red to infrared wavelengths at 1.2–2.5  μm . Spectral measurements from LEISA revealed

15330-478: The mass, energy and distribution of charged particles around Pluto, and is also able to differentiate between protons , electrons , and other heavy ions . Alice is an ultraviolet imaging spectrometer that is one of two photographic instruments comprising New Horizons ' Pluto Exploration Remote Sensing Investigation (PERSI); the other being the Ralph telescope. It resolves 1,024 wavelength bands in

15476-419: The merging of the lobi. At the time of formation, Arrokoth's composition had a higher volatile concentration from the accretion of condensed volatiles within the dense and opaque Kuiper belt. After the surrounding dust and nebula subsided, solar radiation was no longer obstructed, allowing for photon-induced sublimation to occur in the Kuiper belt. Due to Arrokoth's high rotational obliquity, one polar region faces

15622-646: The mission's science objectives are to: The spacecraft is comparable in size and general shape to a grand piano and has been compared to a piano glued to a cocktail bar-sized satellite dish. As a point of departure, the team took inspiration from the Ulysses spacecraft, which also carried a radioisotope thermoelectric generator (RTG) and dish on a box-in-box structure through the outer Solar System. Many subsystems and components have flight heritage from APL's CONTOUR spacecraft, which in turn had heritage from APL's TIMED spacecraft. New Horizons ' body forms

15768-423: The neck would be excessively compressed by the mutual gravity of the lobi such that the entire object would gravitationally collapse into a spheroid . Arrokoth is thought to have formed from two separate progenitor objects that formed over time from a rotating cloud of small, icy bodies since the formation of the Solar System 4.6 billion years ago. Arrokoth had likely formed in a colder environment within

15914-442: The neck. The brightness of Akasa is thought to be maintained by high seasonal axial tilt as Arrokoth orbits around the Sun. Over the course of its orbit, Akasa Linea is shadowed when the lobi are coplanar to the direction of the Sun, at which times the neck region receives no sunlight, cooling and trapping volatiles in the region. In May 2020, the IAU's Working Group for Planetary System Nomenclature (WGPSN) formally established

16060-440: The objects found were reachable by the New Horizons spacecraft and most Kuiper belt objects that may be suitable were just too distant and faint to be seen through Earth's atmosphere. In order to find these fainter Kuiper belt objects, the New Horizons team initiated a search for suitable targets with the Hubble Space Telescope on 16 June 2014. Arrokoth was first imaged by Hubble on 26 June 2014, 10 days after

16206-664: The one-way transit time for radio signals between Earth and New Horizons was 6 hours. The science objectives of the flyby include characterizing the geology and morphology of Arrokoth, and mapping the surface composition (searching for ammonia, carbon monoxide, methane, and water ice). Surveys of the surrounding environment to detect possible orbiting moonlets, a coma, or rings, were conducted. Images with resolutions showing details of 30 m (98 ft) to 70 m (230 ft) are expected. From Hubble observations, faint, small satellites orbiting Arrokoth at distances greater than 2,000 km (1,200 mi) have been excluded to

16352-437: The orbit to be highly uncertain, with an uncertainty parameter of 5. Arrokoth is generally classified as a distant minor planet or trans-Neptunian object by the Minor Planet Center as it orbits in the outer Solar System beyond Neptune. Having a non-resonant orbit within the Kuiper belt region 39.5–48 AU from the Sun, Arrokoth is formally classified as a classical Kuiper belt object , or cubewano. Arrokoth's orbit

16498-418: The predicted ground track of the occultation shadow in southern Argentina ( Chubut and Santa Cruz provinces) to better constrain the size of Arrokoth. The average spacing between these telescopes was around 4 km (2.5 mi). Using the latest observations from Hubble, the position of Arrokoth was known with much better precision than for the 3 June occultation, and this time the shadow of Arrokoth

16644-416: The presence of methanol and complex organic compounds on the surface of Arrokoth, but no evidence of water ice. One particular absorption band in Arrokoth's spectrum at 1.8 μm indicates that these organic compounds are sulfur -rich. Given the abundance of methanol on Arrokoth's surface, it is predicted that formaldehyde -based compounds resulting from irradiation should also be present, albeit in

16790-462: The probe on a solar-escape trajectory at 16.26 kilometers per second (58,536 km/h; 36,373 mph). New Horizons took only nine hours to pass the Moon's orbit. Although there were backup launch opportunities in February 2006 and February 2007, only the first twenty-three days of the 2006 window permitted the Jupiter flyby. Any launch outside that period would have forced the spacecraft to fly

16936-402: The probe runs on Nucleus RTOS operating system. There have been two "safing" events, that sent the spacecraft into safe mode : Communication with the spacecraft is via X band . The craft had a communication rate of 38 kbit/s at Jupiter; at Pluto's distance, a rate of approximately 1  kbit/s per transmitter was expected. Besides the low data rate, Pluto's distance also causes

17082-403: The quantity of reflected light in visible spectrum, is measured at 21 percent, typical for most Kuiper belt objects. The overall Bond albedo (the quantity of reflected light of any wavelength) of Arrokoth is measured at 6.3 percent. The surface of Arrokoth is lightly cratered and smooth in appearance. Arrokoth's surface has few small craters (from 1 km (0.62 mi) in size to

17228-467: The reduced wattage; still, not all instruments can operate simultaneously. The Department of Energy transferred the space battery program from Ohio to Argonne in 2002 because of security concerns. The amount of radioactive plutonium in the RTG is about one-third the amount on board the Cassini–Huygens probe when it launched in 1997. The Cassini launch had been protested by multiple organizations, due to

17374-416: The risk of such a large amount of plutonium being released into the atmosphere in case of an accident. The United States Department of Energy estimated the chances of a launch accident that would release radiation into the atmosphere at 1 in 350, and monitored the launch because of the inclusion of an RTG on board. It was estimated that a worst-case scenario of total dispersal of on-board plutonium would spread

17520-625: The search for hazardous material were presented on the 49th Meeting of the AAS Division for Planetary Sciences , on 20 October 2017. On 17 July 2017, the Hubble Space Telescope was used to check for debris around Arrokoth, setting constraints on rings and debris within the Hill sphere of Arrokoth at distances of up to 75,000 km (47,000 mi) from the main body. For the third and final occultation, team members set up another ground-based "fence line" of 24 mobile telescopes along

17666-468: The size and shape of Arrokoth. Hubble observations were carried out on 4 August 2018, to support the occultation campaign. Hubble could not be placed in the narrow path of the occultation, but due to the favourable location of Hubble at the time of the event, the space telescope was able to probe the region down to 1,600 km (990 mi) from Arrokoth. This is much closer than the 20,000 km (12,000 mi) region that could be observed during

17812-615: The small ones (previously used on Cassini and the Voyager spacecraft) are used primarily for attitude control and spinup/spindown maneuvers. Two star cameras are used to measure the spacecraft attitude. They are mounted on the face of the spacecraft and provide attitude information while in spin-stabilized or 3-axis mode. In between the time of star camera readings, spacecraft orientation is provided by dual redundant miniature inertial measurement units . Each unit contains three solid-state gyroscopes and three accelerometers . Two Adcole Sun sensors provide attitude determination. One detects

17958-635: The smaller lobus "Thule". They are now formally named "Wenu" and "Weeyo", respectively. In November 2019, the International Astronomical Union (IAU) announced the object's permanent official name, Arrokoth . The name Arrokoth was chosen by the New Horizons team to represent the Powhatan people indigenous to the Tidewater region of Virginia and Maryland in the eastern United States. The Hubble Space Telescope and

18104-431: The smaller lobus, Weeyo, is measured at 15.4 km (9.6 mi) across its longest axis. Wenu is lenticular in shape, being highly flattened and moderately elongated. Based on shape models of Arrokoth constructed from images taken by the New Horizons spacecraft, the dimensions of Wenu are approximately 21 km × 20 km × 9 km (13.0 mi × 12.4 mi × 5.6 mi). In contrast, Weeyo

18250-439: The space probe back to Earth took four hours and 25 minutes to traverse 4.7 billion km of space. Part of the reason for the delay between the gathering of and transmission of data is that all of the New Horizons instrumentation is body-mounted. In order for the cameras to record data, the entire probe must turn, and the one-degree-wide beam of the high-gain antenna was not pointing toward Earth. Previous spacecraft, such as

18396-630: The surface displays subtle color variation among its surface features. Spectral images of Arrokoth show that the Akasa (neck) region and lineation features appear less red compared to the central region of the smaller lobe Weeyo. The larger lobe Wenu also displays redder regions, informally known as "thumbprints" by the New Horizons team. The thumbprint features are located near Wenu's limb. The surface albedo or reflectivity of Arrokoth varies from 5 percent to 12 percent due to various bright features on its surface. Its overall geometric albedo ,

18542-548: The tenuous solar wind at Pluto's distance, the instrument is designed with the largest aperture of any such instrument ever flown. Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) is a time of flight ion and electron sensor that makes up one of the two instruments comprising New Horizons ' plasma and high-energy particle spectrometer suite (PAM), the other being SWAP. Unlike SWAP, which measures particles of up to 6.5 keV, PEPSSI goes up to 1 MeV. The PEPSSI sensor has been designed to measure

18688-476: The transmitters in the 2030s. There are no onboard batteries since RTG output is predictable, and load transients are handled by a capacitor bank and fast circuit breakers. As of January 2019, the power output of the RTG is about 190  W . The RTG, model " GPHS-RTG ", was originally a spare from the Cassini mission. The RTG contains 9.75 kg (21.5 lb) of plutonium-238 oxide pellets. Each pellet

18834-525: The two progenitor objects had merged very slowly at a speed of 2 m/s (6.6 ft/s)—comparable to the average walking speed of a person. The progenitor objects must have also merged obliquely at angles greater than 75 degrees in order to account for the present shape of Arrokoth's thin neck while keeping the lobi intact. By the time the two progenitor objects merged, both of them had already been tidally locked in synchronous rotation . The long-term frequency of impact events occurring on Arrokoth

18980-483: The universe. The dust counter is named for Venetia Burney , who first suggested the name "Pluto" at the age of 11. A thirteen-minute short film about the VBSDC garnered an Emmy Award for student achievement in 2006. The Radio Science Experiment (REX) used an ultrastable crystal oscillator (essentially a calibrated crystal in a miniature oven ) and some additional electronics to conduct radio science investigations using

19126-408: The unseen sections of Arrokoth occulted background stars, scientists were able to then outline the shapes of both lobi. The cause of Arrokoth's unexpectedly flattened shape is uncertain, with various explanations including sublimation or centrifugal forces . The longest axes of the lobi are nearly aligned with the rotational axis , which is situated between them. This near-parallel alignment of

19272-518: The volume ratio of Wenu to the smaller Weeyo is approximately 1.9:1.0, meaning that Wenu's volume is nearly twice that of Weeyo. Overall, the volume of Arrokoth is around 3,210 km (770 cu mi), though this estimate is largely uncertain due to weak constraints on the thicknesses of the lobi. Prior to the New Horizons flyby of Arrokoth, stellar occultations by Arrokoth had provided evidence for its bilobate shape. The first detailed image of Arrokoth confirmed its double-lobed appearance and

19418-424: The world where they could see Arrokoth cover up a different star on each of these dates. Based on this string of three occultations, scientists were able to trace out the object's shape. In June and July 2017, Arrokoth occulted three background stars. The team behind New Horizons formed a specialized "KBO Chasers" team led by Marc Buie to observe these stellar occultations from South America, Africa, and

19564-513: Was accompanied by an orbiting moonlet about 200–300 km (120–190 mi) away from the primary. It was later realized, however, that an error with the data processing software resulted in a shift in the apparent location of the target. After accounting for the bug, the short dip observed on 10 July was considered to be a detection of the primary body. By combining data about its light curve , spectra (e.g. color), and stellar occultation data, illustrations could rely on known data to create

19710-421: Was based largely on Stern's work since Pluto 350 and involved most of the team from Pluto Kuiper Express . The New Horizons proposal was one of five that were officially submitted to NASA. It was later selected as one of two finalists to be subject to a three-month concept study in June 2001. The other finalist, POSSE (Pluto and Outer Solar System Explorer), was a separate but similar Pluto mission concept by

19856-450: Was described as a "snowman" by Alan Stern, as the lobi appeared distinctively spherical. On 8 February 2019, one month after the New Horizons flyby, Arrokoth was found to be more flattened than initially thought, based on additional images of Arrokoth taken by New Horizons after its closest approach. The flattened lobus Wenu was described as a "pancake", while Weeyo was described as a "walnut" as it appeared less flattened. By observing how

20002-574: Was discovered on 26 June 2014 using the Hubble Space Telescope during a preliminary survey to find a suitable Kuiper belt object for the New Horizons spacecraft to fly by. Scientists of the New Horizons team were searching for an object in the Kuiper belt that the spacecraft could study after Pluto, and their next target had to be reachable on New Horizons 's remaining fuel. Using large ground-based telescopes on Earth, researchers began looking in 2011 for candidate objects and searched multiple times per year for several years. However, none of

20148-665: Was finally able to start building the spacecraft and its instruments, with a planned launch in January 2006 and arrival at Pluto in 2015. Alice Bowman became Mission Operations Manager (MOM). New Horizons is the first mission in NASA's New Frontiers mission category, larger and more expensive than the Discovery missions but smaller than the missions of the Flagship Program. The cost of the mission, including spacecraft and instrument development, launch vehicle, mission operations, data analysis, and education/public outreach,

20294-464: Was low due to the slower speeds of objects in the Kuiper belt. Over a period of 4.5 billion years, photon-induced sputtering of water ice on Arrokoth's surface would minimally reduce its size by 1 cm (0.39 in). With the lack of frequent cratering events and perturbations of its orbit, the shape and appearance of Arrokoth would remain virtually pristine since the conjoining of two separate objects that formed its bilobate shape. Arrokoth

20440-509: Was originally planned as a voyage to the only unexplored planet in the Solar ;System. When the spacecraft was launched, Pluto was still classified as a planet , later to be reclassified as a dwarf planet by the International Astronomical Union (IAU). Some members of the New Horizons team, including Alan Stern, disagree with the IAU definition and still describe Pluto as the ninth planet. Pluto's satellites Nix and Hydra also have

20586-406: Was published in the summer of 2002. New Horizons topped the list of projects considered the highest priority among the scientific community in the medium-size category; ahead of missions to the Moon, and even Jupiter. Weiler stated that it was a result that "[his] administration was not going to fight". Funding for the mission was finally secured following the publication of the report. Stern's team

20732-626: Was successfully observed by at least five of the mobile telescopes. Combined with the SOFIA observations, this put constraints on possible debris near Arrokoth. Results from the occultation on 17 July showed that Arrokoth could have had a very oblong, irregular shape or be a close or contact binary. According to the duration of the observed chords , Arrokoth was shown to have two "lobes", with diameters of approximately 20 km (12 mi) and 18 km (11 mi), respectively. A preliminary analysis of all collected data suggested that Arrokoth

20878-489: Was the 1745th minor planet to be assigned a provisional designation during the second half of June 2014. After further observations refining its orbit, it was given the permanent minor planet number 486958 on 12 March 2017. Before the flyby on 1 January 2019, NASA invited suggestions from the public on a nickname to be used for the object. One of the choices, Ultima Thule , was selected on 13 March 2018. Thule ( Ancient Greek : Θούλη , Thoúlē )

21024-521: Was the fastest (average speed with respect to Earth) human-made object ever launched from Earth. It is not the fastest speed recorded for a spacecraft, which, as of 2023, is that of the Parker Solar Probe . After a brief encounter with asteroid 132524 APL , New Horizons proceeded to Jupiter , making its closest approach on February 28, 2007, at a distance of 2.3 million kilometers (1.4 million miles). The Jupiter flyby provided

21170-478: Was the search for hazardous material like rings or dust near Arrokoth that could threaten the New Horizons spacecraft during its flyby in 2019. Data collection was successful. A preliminary analysis suggested that the central shadow was missed; only in January 2018 was it realized that SOFIA had indeed observed a very brief dip from the central shadow. The data collected by SOFIA will also be valuable to put constraints on dust near Arrokoth. Detailed results of

21316-404: Was used as an opportunity for science outreach . Despite some stations being affected by bad weather, the event was successfully observed, as reported by the New Horizons team. Initially, it was unclear whether a chord on the target had been recorded. On 6 September 2018, NASA confirmed that the star had indeed been seen to dip by at least one observer, providing important information about

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